It depends on what they are looking for. For example, a company could gather information about your browsing habits using advertising. If a company like Google distributes ads across a wide variety of sites, they can use your fingerprint to gather lots of information about your browsing habits.
This is scary not because it enables them to provide more relevant ads, but because it enables them to sell personal information to organizations like corporations and the government. Imagine your boss being able to buy a package that tells him what type of porn you like, how often you view porn, your most visited subreddits, etc.
And often from this information, these companies (based on aggregate data) can make more sweeping generalizations (that are often incorrect, but also often right on the mark) like income bracket, ethnicity, drug use habits, sexual orientation, etc. These approximations can also be bought.
Imagine that your 'package' has some information in it deducing that you regularly use cocaine. Even if this is not true and the person observing this information knows it might not be true, the fact that it has been stated might be enough to lose you some important opportunity.
I don't know how common it is for someone to buy this information, but I know that the information is already out there and the potential for things like this is very large.
This is scary not because it enables them to provide more relevant ads, but because it enables them to sell personal information to organizations like corporations and the government. Imagine your boss being able to buy a package that tells him what type of porn you like, how often you view porn, your most visited subreddits, etc.
And often from this information, these companies (based on aggregate data) can make more sweeping generalizations (that are often incorrect, but also often right on the mark) like income bracket, ethnicity, drug use habits, sexual orientation, etc. These approximations can also be bought.
Imagine that your 'package' has some information in it deducing that you regularly use cocaine. Even if this is not true and the person observing this information knows it might not be true, the fact that it has been stated might be enough to lose you some important opportunity.
I don't know how common it is for someone to buy this information, but I know that the information is already out there and the potential for things like this is very large.